“Brain.exe has stopped working” became a famous meme on Reddit post-2010s, mimicking the classic Windows crash alert pop-up. It was a way to describe brain fog, when the brain literally “crashes” and has a hard time processing information and drawing inferences. Now, neural imaging and psychological testing show that under acute stress, your brain can buckle and crash. In fact, the effects don’t just stay during the stressful situation, like a job interview, but can linger longer. The study was published in Science Advances.
Connecting the Dots
The brain picks up new information daily, and connects it to old ones to make inferences through a cognitive process called integration. For example, if you have the memory of a friend who goes to a dog park with a golden retriever, and you see a golden retriever in the dog park, you might integrate the memory with the visual input to deduce that your friend is probably there. As easy as it sounds, individuals with mental-health conditions like psychosis and anxiety disorders can actually have trouble connecting these two pieces of information.
The hippocampus is a vital brain region for integration, but it is also highly susceptible to stress. Lars Schwabe, a cognitive psychologist at the University of Hamburg in Germany, and his colleagues decided to study the effects of acute stress on the brain’s ability to deduce and infer.
Setting the Memory Task Experiment
On the first day, 121 participants were asked to memorize a series of paired images, each wiith an image of an animal and another image of either a face or a scene. The next day, roughly half od the participants were put on a mock job interview that required them to convince that they are suitable for a hypothetical role, and perform complex mental mathematics. The other group took part in the control, had to give a speech about a topic of their choice and complete a simple mental maths task.
Afterwards, participants were presented with another series of paired images, this time, each pair had an image of an animal and that of a 3D shape. Then, the participants were shown, one-by-one, the 3D shapes that they previously saw alongside a collection of various faces and scenes. Then they were asked to select the face or scene that they found most likely to be associated with each 3D shape.
Let’s say an individual have memorized a pair with a cat and a mountain scene on the first day and a pair with a blue cube on the second. If the person’s brain had successfully integrated the memories from the two separate days, then they should find that the forest scene corresponds most with the blue cube.
Real-time Imaging offers Clues
To understand what was going on in the participant’s brains, Schwabe and his colleagues used a method called functional magnetic resonance imaging or fMRI to get a real-time view of brain activity. As a baseline, the researchers used fMRI to point out the parts of the hippocampus that ‘lit up’ when the participants viewed images from the various categories. Animals lit up one region while the 3D shapes another. Faces and scenes excited a different region of the hippocampus.
The high-stress group lagged behind in activity when they looked at the 3D shape, compared to the area that corresponded to the faces and scenes. This suggests that their brain had not inferred the connection between the shape and the face or scene. Even so, the accuracy of the stressed participants when deducing which face or scene was linked to a specific 3D shape was the same as that of the control-group participants. The authors link this to what the fMRI is used to observe— memory linkages, rather than behavioral tests.
“Normally when you encode something new, there’s this little flicker of the past experience coming to mind, and we think that’s what supports the integration,” says Brice Kuhl, a neuroscientist at the University of Oregon in Eugene. “That flicker is basically missing” in the stressed participants.
The next step for Schwabe and his colleague involves experiments on rodents to understand the mechanism that induces this phenomenon, and find ways to reduce the effects of stress.
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